Well, my car's cup holders would work if they were big enough to fit McDonalds' super size drinks.
They work OK for small and medium ones.
But there's only 2 of them. That kinda makes it hard to fit them all in there if you're buying for the whole family. Sometimes I just have to trust McDonalds' crappy cup holders made out of paper.
I wouldn't have to pick up bad driving habits if I would drive slow enough that just sitting the drinks in the passenger seat would be sufficient, but if I drive that slow, I piss off more people than I'd piss off by having to slow down a little more to make turns.